三金属MgCaAl-LDH纳米片:高效Aldol反应催化剂OA

Solid base catalysts have become extremely important due to their key role in various multiphase catalytic reactions.With their structural controllability and ion exchangeability,hydrotalcite have become important players in the field of solid base catalysts.The hydrotalcite materials are layered anionic compounds that can be used as catalysts or catalyst precursors.In this paper,a series of MgxAly-LDH nanosheets were prepared by the coprecipitation method,and the optimum process parameters such as the best anion and Mg/Al molar ratio were selected according to the performance of the Aldol reaction.On this basis,heterometallic M(M=Ca,Mn)doping was carried out by adjusting the fine structure of Mg-O-Al,which subsequently enhanced the basic strength of LDH.The physicochemical properties of the catalysts were analyzed by a combination of characterization tools such as XRD,TEM,XPS,FT-IR,TG and BET,indicating that(Mg0.75Ca0.25)4Al4-LDH and(Mg0.75Mn0.25)4Al4-LDH nanosheet catalysts were successfully obtained.The Aldol reaction was carried out using acetone and benzaldehyde as reaction substrates,and it was found that after the introduction of the heterometallic Ca2+,the basicity of the catalyst was enhanced,the catalytic effect of the Aldol reaction was elevated,and the conversion and yield of the reactants were improved,showing a higher heterogeneous catalytic performance,while on the contrary,after the introduction of Mn2+,it weakened,even more,the alkali strength of its weakly basic sites,leading to the opposite result.